Always use plural names for properties representing collections (arrays/lists) in interfaces, types, and destructuring patterns. This ensures consistency between interface definitions and their usage throughout the codebase. Example: ```typescript // ❌ Inconsistent naming interface DigestEmailProps { newsletter?: EmailItem[]; // singular for array receipt?: EmailItem[]; // singular for array } // ✅ Consistent plural naming interface DigestEmailProps { newsletters?: EmailItem[]; // plural matches array type receipts?: EmailItem[]; // plural matches array type } // Usage remains consistent with interface const { newsletters, receipts } = props; ``` This convention: - Makes array types immediately recognizable - Prevents confusion between single items and collections - Reduces bugs from property name mismatches - Follows common JavaScript/TypeScript conventions